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To: "Scott Marlowe" <scott.marlowe@gmail.com>, "Gael Le Mignot"
	<gael@pilotsystems.net>
Cc: "Craig James" <craig_james@emolecules.com>,
	pgsql-performance@postgresql.org
Subject: Re: Compared MS SQL 2000 to Postgresql 9.0 on Windows
References: <378e24d1e3af88a49fbbb7c4d26f441a@mail.gmail.com>
	<4CFE7964.80206@squeakycode.net>
	<AANLkTi=HiO8ErFwzqBvgjXXHRUMKeUWqCpL-p9Y+oL_-@mail.gmail.com>
	<4CFE8E59.2010505@squeakycode.net>
	<AANLkTin4K86j2-GOUfmdXQ8UKv_j9V8ZRiRBEbbXj+jc@mail.gmail.com>
	<20101207201028.GE4028@aart.is.rice.edu>
	<4CFE97B4.8090708@squeakycode.net>
	<fd4bd31b523753145cf67ae6e6cb4aec@mail.gmail.com>
	<op.vne45kfjeorkce@apollo13>
	<70e424e558d87f649f149bf2948d73cb@mail.gmail.com>
	<4D0B9EB0.1070708@emolecules.com>
	<AANLkTi=wPaT_xVU2JGUg_Sc3taOphP0HW487oJHFafXe@mail.gmail.com>
	<plop87wrn7wk4u.fsf@aoskar.kilobug.org>
Date: Sat, 18 Dec 2010 14:55:26 +0100
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From: "Pierre C" <lists@peufeu.com>
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>  > The real performance problem with RAID 5 won't show up until a drive
>  > dies and it starts rebuilding
>
> I don't  agree with that. RAID5 is  very slow for random  writes, since
> it needs to :

"The real problem" is when RAID5 loses a drive and goes from "acceptable"  
kind of slow, to "someone's fired" kind of slow. Then of course in the  
middle the rebuild, a bad sector is discovered in some place the  
filesystem has never visited yet on one of the remaining drives, and all  
hell breaks loose.

RAID6 is only one extra disk...